Air carrier technician reported after completing a main landing gear brake replacement they were later informed they forgot to reconnect the aft hydraulic line.

Narrative

On the work night of Day 0 ; my crew of four technicians were assigned the overnight maintenance work package for Aircraft X; an A330 aircraft. It was during accomplishment of the service check that the #3 MLG brake assembly was found to be at the maximum wear limit and required replacement. Our four-man crew then decided to split up. This allowed for two technicians to continue working the service check to completion and the other two technicians to accomplish the newly found #3 MLG brake removal and replacement. So; a fellow technician and I were elected to change the #3 brake assembly. Our now two-man crew gathered up the needed tire change cart and the specific A330 AMM (Aircraft Maintenance Manual) reference for the task and started in. Within a short amount of time; we had the right MLG forward bogie jacked and the #3-wheel and tire assembly removed. Then with the #3 brake assembly exposed; we coordinated efforts by one of us working to disassemble the top half of the worn brake while the other man laid underneath the brake and disassembled the bottom side brake rod and torque pin. Within about 15 minutes we had the old #3 brake assembly removed and were ready to install the new brake assembly. Following all required steps per the installation procedure; we again worked in cooperation to position the new brake onto the axel and in reverse order; coordinated to install all the mechanical and hydraulic connections. I again took on assembling the bottom half while my partner took care in assembling the top half of the brake connections. We then re-installed the #3 wheel and tire assembly as required and made ready for hydraulic leak checks. We asked one of our other crew members to run the hydraulic pumps and set and release the brakes a few times while one of us inspected for leaks. Our leak check was successful so we on to task close-up and paperwork to document our corrective action.Sadly; as it was discovered; but unbeknownst to my teammate and myself; the aft hydraulic line connection was not connected to its position on the new #3 brake assembly. Unmistakably; this was a failure by myself and my teammate to properly inspect the final installation. We missed it on double-checking each other's work. All in all; I think maybe we were rushed to start our next task which was to replace the worn #8 wheel and tire assembly and failed to perform a final detailed inspection of the brake installation before moving on to other tasks. This instance should be a valuable reminder to carefully check over or inspect one another's work as we go along or at least at the end of a task. Teamwork includes being vigilant of each other's work so we don't miss steps.This concludes my first-hand account of the recent #3 brake replacement on Aircraft X.